Beyond the incredible quality and quantity of his work starting from early in his life, what makes Terence Tao memorable to me, is his approachability and willingness to write advice for mathematicians and math students in a blog: https://terrytao.wordpress.com/career-advice/
It's rare to see a professional at the top of an academic field remain so encouraging to other people in the field, and work to make their work accessible to colleagues across different levels of mathematical maturity.
He also has an active Mastodon, which further makes him more approachable: https://mathstodon.xyz/@tao
It's rare to see a professional at the top of an academic field remain so encouraging to other people in the field, and work to make their work accessible to colleagues across different levels of mathematical maturity.